From: Luca Barbieri <ldb@ldb.ods.org>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Pavel Machek <pavel@suse.cz>,
Linux-Kernel ML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@transmeta.com>
Subject: Re: [PATCH 1 / ...] i386 dynamic fixup/self modifying code
Date: 30 Aug 2002 01:29:32 +0200 [thread overview]
Message-ID: <1030663772.1491.107.camel@ldb> (raw)
In-Reply-To: <1030663192.1326.20.camel@irongate.swansea.linux.org.uk>
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On Fri, 2002-08-30 at 01:19, Alan Cox wrote:
> On Wed, 2002-08-28 at 13:11, Pavel Machek wrote:
> > > Unfortunately with this patch executing invalid code will cause the
> > > processor to enter an infinite exception loop rather than panic. Fixing
> > > this is not trivial for SMP+preempt so it's not done at the moment.
> >
> > Using 0xcc for everything should fix that, right?
>
> Except you can't do the fixup on SMP without risking hitting the CPU
> errata.
Worked around by making sure all other processors are stopped (iret is
serializing) sending IPIs if they are not already spinning on the fixup
lock. See patch #2.
> You also break debugging tools that map kernel code pages r/o
> and people who ROM it.
>
> The latter aren't a big problem (they can compile without runtime
> fixups).
OK, I'll add a config option for this.
> For the other fixups though you -have- to do them before you
> run the code. That isnt hard (eg sparc btfixup). You generate a list of
> the addresses in a segment, patch them all and let the init freeup blow
> the table away
Is doing them at runtime with the aforementioned workaround fine?
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next prev parent reply other threads:[~2002-08-29 23:25 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-28 3:41 [PATCH 1 / ...] i386 dynamic fixup/self modifying code Luca Barbieri
2002-08-28 12:11 ` Pavel Machek
2002-08-29 22:57 ` Luca Barbieri
2002-08-29 23:19 ` Alan Cox
2002-08-29 23:22 ` Pavel Machek
2002-08-30 0:05 ` David S. Miller
2002-08-30 0:21 ` Luca Barbieri
2002-08-29 23:29 ` Luca Barbieri [this message]
2002-08-29 23:32 ` Alan Cox
2002-08-30 0:10 ` Luca Barbieri
2002-08-30 11:17 ` Alan Cox
2002-09-03 21:31 ` Jamie Lokier
2002-09-03 21:35 ` Jamie Lokier
2002-08-30 0:08 ` David S. Miller
2002-08-28 15:53 ` Mikael Pettersson
2002-08-28 16:16 ` Luca Barbieri
2002-08-28 19:48 ` Mikael Pettersson
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